1. Field of the Invention
The present invention relates to a power supply apparatus capable of bidirectionally supplying power, and more particularly, to a power supply apparatus for an electric vehicle.
2. Description of the Related Art
Demand for vehicles is explosively increasing in accordance with economic progress. Because of the increase in demand for vehicles and use thereof, vehicle exhaust emissions are main causes of environmental pollution.
In this regard, the need for reductions in vehicle exhaust emissions has continued, and so research into and development of methods of reducing vehicle exhaust emissions have been conducted. Furthermore, attempts to commercialize electric vehicles that do not emit exhaust gasses have been partially made.
Electric vehicles are vehicles that operate using electricity as a motive power source, have a rechargeable battery mounted therein as the power supply, and operate by using power supplied from the mounted battery.
Such electric vehicles generally include an electric motor driven by electricity and used as a power source for operating electric vehicles instead of an internal combustion engine, and a battery supplying electricity to the electric motor in order to drive the electric motor.
Recently, a plug-in charging method has mainly been used and developed so as to supply electricity to a battery and allow the battery to be charged. The plug-in charging method is a method of supplying power to the battery for the charging thereof through a plug-in charging apparatus and operating electric vehicles by using the battery.
The charging of an electric vehicle battery using the plug-in charging method requires a relatively long period of time and a vehicle may have limited mileage with one battery charge. It generally takes about 1-8 hours to charge electric vehicles, leading to a defect in that it may be difficult to safely manage electric vehicles during such a long charging period of time.
Therefore, electric vehicles should be frequently charged so as to secure a target moving distance, and thus, building charging stations and charging systems are very important in operating electric vehicles.
Further, electric vehicles should be charged without being influenced by external environmental conditions such as rain, snow, and the like, during charging. Furthermore, in a case in which the charging system of electric vehicles is constructed in the same manner as current gas stations, it is impossible to meet charging demand.
As described above, the necessity of establishing a charging system suitable for electric vehicles is emerging as a major issue in the commercialization of electric vehicles.
As the charging system of electric vehicles, a bidirectional charging apparatus for supplying power during electrical charging at a charging station and supplying power from a battery after charging is complete is disclosed in the prior art document. However, there is a limitation in that a circuit area and manufacturing costs may be increased due to the weight and volume of a transformer that is a core element in the bidirectional charging apparatus. Further, circuits for supplying power to electric vehicles are additionally necessary, which also further increases circuit area and manufacturing costs.